Lawn mowers include an autonomous lawn mower capable of autonomously traveling without being steered by a worker. This autonomous lawn mower can automatically travel on the lawn by traveling wheels, and mow the lawn by a cutter blade which rotates almost horizontally, and is known as a so-called robotic lawn mower. A lawn mower like this is known from European Patent Application Publication No. 2656719.
This lawn mower known from European Patent Application Publication No. 2656719 has the arrangement of an autonomous lawn mower (robotic lawn mower) capable of air-cooling the interior. The lawn mower includes a motor having a downward rotating shaft, a motor holding member holding the motor, a holding member mounting unit in which the motor holding member is mounted to be vertically movable, a traveling frame having the holding member mounting unit, and a cover covering the traveling frame from above. A lawn mowing unit is attached to the rotating shaft of the motor. The lawn mowing unit is positioned below the traveling frame, and can mow the lawn by horizontally rotating. Traveling wheels for automatic traveling are attached to the traveling frame.
A space formed by the traveling frame and cover accommodates various electric parts such as the motor, a batter, and electronic components. To air-cool these electric parts, external air is taken in through a vent hole of the cover. Air having cooled the electric parts is exhausted from the bottom surface of the traveling frame through an opening at the lower end of the holding member mounting unit.
When lawn mowing is performed by the lawn mower, cut grass and mud can attach to the bottom surface of the traveling frame and the lawn mowing unit. To clean up the lawn mower, the bottom surface of the traveling frame and the lawn mowing unit need only be washed with high-pressure cleaning water. However, the lower end of the holding member mounting unit is exposed from the bottom surface of the traveling frame. In addition, the opening for exhausting air having cooled the electric parts is formed in the lower end of the holding member mounting unit. To solve this problem, some waterproof device can be formed to prevent the cleaning water from entering the interior of the lawn mower. However, if the waterproof device is formed, the waterproof structure may become complicated, and the cost of the lawn mower increases, so some improvement is necessary.